Retractable gear problem / Blender

[Darby]

Hi

I'm building an English Electric Lightning and the modelling and mapping in Blender have been going good [See attached image Lightning_Blender_Gear_Down.png]

However, I've hit a problem when adding the retractable gear and wondered if anyone else had seen/experienced the same problem where the left gear seems to rotate at the wrong angles.

I've built the gear bays and have added a simple gear model to test the retractable angles that I need to store the gear away flushly. The gear has to rotate on the Y and Z axis to fit back into the bays on the swept wings.

I've modelled the NUP properties and the .sup file associated with the .3ds is set as follows:

[~CS_RG]
IsPivot=BOOL:No
NUP_MaxRotationXDEG=FLOAT:0.
NUP_MaxRotationYDEG=FLOAT:-88.5
NUP_MaxRotationZDEG=FLOAT:60.
Name=STRING:~CS_RG
Parent=STRING:~CS_RMW
Pivot=STRING:

[~CS_LG]
IsPivot=BOOL:No
NUP_MaxRotationXDEG=FLOAT:0.
NUP_MaxRotationYDEG=FLOAT:88.5
NUP_MaxRotationZDEG=FLOAT:-60.
Name=STRING:~CS_LG
Parent=STRING:~CS_LMW
Pivot=STRING:

When these angles are applied in Blender, the gear retracts nicely and uniformly [See Lightning_Blender_Gear_Up.png] as these values are symetrically equivalent.

When the model is in RealFlight, the gear down geometry is correct and the NUP values are shown correctly when I edit the plane in RF [See Lightning_RF_Gear_Down.png]. Therefore, I've assumed that the .3ds, .sup and .kex files are being generated and converted correctly.

However, when I retract the gear in real flight, the front and right-side gear retract perfectly but both the left gear leg and the left wheel appear to rotate at the wrong angle and protrude through the left wing. Both wings are geometrically the same and mirored [See Lightning_RF_Gear_Up.png and Lightning_RF_Gear_Up2.png]

I have tried producing the left gear by duplicating and mirroring the working right-side gear and the same effect happens. I have modelled the left gear seperately and the same happens. It's almost like there is some geometry in the model that is interfering and I've spent the last 7 days trying to fix this

Has anyone seen this weird behaviour before? Any ideas on where to look/how I might fix greatfully received

Many thanks,
Darby

 

[abaser]

Having never done retracts this is just a guess, but I have three questions.

1) Are you showing the same gear in blender as RF? The ones in blender look round, but in RF they look square.

2) Is it possible your model is slightly shifted off center?

3) Is your parenting consistent?

 

[Darby]

Hey abaser, Thanks for your comments.

1. I changed the mapping slightly and put black tread on the tyre, but they are the same gear
2. I'll check this
3. Parent - yep - parenting is [wheel] -- [gear leg] --- [wing] -- [fuse] in both cases.

Its weird - if I move the right gear leg over to the left, it then works. Something is interfereing with the ~CS_LG I suspect.

 

[Madratter]

Hmm, I have also not done retractable gear. That said, my guess would be a misplaced pivot point.

 

[bosshawg]

Mult-Axis Retract Thread

Multi-Axis Retract Thread This might help

 

[Darby]

Cheers for the suggestion Madratter, checked the pivots on both gear legs and they were Ok.

Abaser - you had noticed that the whole mesh was off-centre very sightly. Once I centred this both gear became out of alignment when imported. I then tried selecting all elements and moving the mesh in the y axis in blender and this had no effect. However, moving the mesh in the z axis had an effect. I first moved it to far, which had a reverse effect. By nudging a few times I've settled at a z-location that enables the wheels to retract correctly. Very odd...

So... I think this is a blender quirk and the position of the mesh in blender effects the rotation point of the wheels, but only if they rotate in 2+ axis (as this doesn't happen for my first model, an F-117, which rotates gear only in 1 axis).

Thanks (again ) for pointing me in the right direction.

Darby

 

[Darby]

bosshawg - great link - many thanks for this - you must of posted this as I was replying to an earlier post

I need to do some reading as I have managed to find a chance solution without undersanding the reasoning behind this - the link and referenced sub-links are packed with the background and the science I need to know behind the subject.

Phew - nearly there - I didn't want to abandon the plane as it handles well